   "Supplies a sub-tree of `db` to the handler. A narrowed view.
   Assumes \"pure\" is in the middleware pipeline prior.
   Grafts the result back into db.
-  If a get-in of the path results in a nil, then \"default-fn\" will be called to supply a value."
+  If a get-in of the path results in a nil, then \"default-fn\" will be called to supply a value.
+  XXX very like update-in. Should the name be more indicative of that closeness? "
   ([p]
     (path p hash-map))
   ([p default-fn]


;; See docs in the Wiki: https://github.com/Day8/re-frame/wiki

(defn noop
  "Middleware which does nothing"
  [handler]
  handler)

(defn pure
  "Acts as an adaptor, allowing handlers to be writen as pure functions.


(defn debug
  "Middleware which logs debug information to js/console for each event.
  Includes a clojure.data/diff of the db, before vs after, showing the changes
  caused by the event."
  [handler]
  (fn new-handler
    [db v]
